n = int(input())
A = list(map(int, input().split()))
l_ma = 0
r_mi = n - 1
dic = {}

for i, a in enumerate(A):
    if a not in dic:
        dic[a] = i
    else:
        j = dic[a]
        if j == -1:
            print(0)
            print()
            exit()
        l_ma = max(l_ma, j)
        r_mi = min(r_mi, i)
        dic[a] = -1

ans = [i for i in range(l_ma + 1, r_mi + 1)]
print(len(ans))
print(*ans)